InterviewSolution
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InterviewSolution
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Let `0A. `6pi`B. `7pi`C. `8pi`D. `4pi` |
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Answer» Correct Answer - A `3+3 cos theta =2 -2 cos^(2) theta` `rArr 2 cos^(2) theta+3 cos theta+1=0` `rArr (2 cos theta+1) (cos theta+1) =0` `:. Cos theta=-1 or cos theta=-1/2` If `cos theta=-1` then `theta=pi, 3 pi, 5 pi, 7 pi, 9pi`, ... If `cos theta=-1//2` then `theta=(2pi)/3, (4pi)/3, (8pi)/3, (10 pi)/3, (14 pi)/3, ...` Solution in increasing order are `(2pi)/3 lt pi lt (4pi)/3 lt (8 pi)/3 lt 3pi lt (10 pi)/3 lt (14 pi)/3 lt 5pi`, ... `:. theta_(3)+theta_(7)=(4pi)/3+(14 pi)/3=6pi` |
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